This invention relates broadly to spring operated re-wind mechanisms which are used in a great variety of domestic, industrial and power plant applications such, for example, as pull cord engine starters, hose reels, vacuum cord reels and the like, and it will be described in this specification in connection with a pull cord type engine starter mechanism.
Starter mechanisms of the pull cord type for use with mowers, outboard marine engines and the like are conventionally provided with a re-wind mechanism for returning the pull cord and its pulley to their at-rest positions, and known devices of this type almost universally use a spiral power spring as the means for providing the re-winding energy. A typical re-wind mechanism is disclosed in the patent to Mack, U.S. Pat. No. 2,564,787, and it will be seen that it includes a spiral power spring which in its normal operative position is in a spiral configuration positioned adjacent an annular retainer for the spring. Operation of the pull cord in such a mechanism causes the spring to be at least partially wound down on the central shaft from its normal position, thus storing energy which is utilized on release of the pull cord to re-wind the cord on its pulley and return the parts to condition for another start.
In addition to the spiral power spring another spiral spring is available commercially under the trademark Spirator and is described and claimed in the United States patents to Foster U.S. Pat. Nos. 2,833,027 and 2,833,534. This spring is backwound in its normal condition and throughout its entire range of operation, being normally in engagement with and bearing outwardly against a cylindrical retainer and being wound down onto a central shaft to store energy which is delivered upon return of the spring to its normal condition. This type of spring can produce much greater energy than the power spring but it is unstable in all conditions and requires special handling, and for this reason its use in re-wind mechanisms has not been proposed as it has been assumed that such use would not be possible without danger to persons installing the springs or servicing the motors, or to users.
It has therefore been the principal object of this invention to provide a spring operated re-wind mechanism which incorporates a background spring but is provided in a configuration which is not only safe to handle but permits easy and quick installation and replacement.